A method of starlight navigation using the infrared horizon sensor

In order to reduce the influence of infrared horizon sensors on starlight navigation precision, the research on measuring errors of attitude angle caused by Earth oblateness is presented by developing the compensation function of oblateness. Meanwhile, the error model of attitude angle based on geocentric vector is designed. The geocentric vector is modified by correcting the inaccuracy of the oblateness, and the geocentric vector offset is adjusted by the attitude control instructions for the satellite. According to the SODERN's Earth infrared radiation model, the real infrared radiation curve including the changes of the infrared radiation intensity with latitude and season is established, thus the accurate information of the Earth edge is obtained by means of filtering algorithm. Moreover, the measuring accuracy of the infrared horizon sensors can be improved effectively. Simulation results show the validity of the proposed strategy to improve the reliability and precision of the starlight navigation based on the scanning infrared horizon sensor. The navigation position error is 500 m, which means the precision is triple better than the traditional method.